FIG 1. Case 1: 32-year-old woman with retroorbital headache and a long history of sinus disease.

A, Schematic representation of a sagittal section through the sphenoidal sinus (S) shows the relationship between Onodi cell (arrows), optic nerve (O), and pituitary gland (P). (Reprinted with permission from [7].)

B, T1-weighted (516/14/2 [TR/TE/excitations]) conventional spin-echo MR image shows an area of increased signal intensity (arrow) anterior and superior to the sphenoidal sinus (S), corresponding to the Onodi cell seen in A. Note that this is part of the posterior ethmoidal air cells (arrowhead).

C, Axial T1-weighted image (600/14/2) shows the mucus-filled Onodi cell extending into the left anterior clinoid process (arrow) and inferior to the optic nerve (arrowheads). Note that on axial images the optic nerve appears to course through the mucocele.

D, Coronal T1-weighted (550/14/2) (top) and T2-weighted (3700/105/2) (bottom) fast spin-echo MR images show that the mass (arrow) underlying the optic nerve (arrowhead) is of high signal intensity on the T1-weighted sequence and of intermediate intensity on the T2-weighted sequence.